Adhesive for use as tile cements and the like



Patented Nov. 18, 1947 UNITED STATE S PATENT OFFICE assess-1 ADHESIVEFOR- USE AS TILE CEMENTS AND THE LIKE Gordon F. Lindner, Royal Oak,Mich, and Harvey J. Livermore, St. Paul, Minn assignors to MinnesotaMining 8; Manufacturing Company, St. laul, Minn., a corporation oiDelaware No Drawing. Application December Serial No. 567,310

6 Claims. (or. 106-241) have failed to provide a composition or cementhaving advantageous combined properties. For

hesion to a wide variety oi structural materials,

when dried in contact therewith.

The objects oi this invention comprise the production of a cement oradhesive or improved characteristics in; one or more of the respectsjust .mentioned. ilidditionally it is an object of the *presentinvention to provide an adhesive comexample, one composition might havefairly ,sat-

isfactory properties in the form of the final dried film but might lackdesired application characteristics and/or suitable wet strength orother properties. Another composition might have passable applicationcharacteristics but a tend-- ency, for example in the case or lacqueredtile, to soak or permeate through the back of the tile and to attack thelacquered surface thereof, thus injuring its appearance and causing whatis frequently termed in the trade as orange-peel." Other compositionsmay be deficient in still other important properties. A salient purposeof the present invention, insofar as it is directed to tile cements oracoustical cements or like compositions, is to provide cements of suchgeneral type which have a new, improved and advantageous combination ordesired properties, as a whole.

Desired properties in adhesive or cement compositions used as tilecements or the like include suitable color, good transferability(ability to readily wet and form a bond with the surface of an objectapplied there-against) a long bonding time, drying characteristics suchthat tiles or the like will not be loosened while the cement is setting,suitable consistency or buttery character,high initial wet strength ofthe freshly applied cement, suificient water resistance in the form ofthe final dried film to withstand the action of water and/or steam suchas may occur in bath showers, for example, suflicient heat resistance inthe form of the final dried film to withstand temperatures up to about140 F., or so, while still retaining a high strength, freedom frombrittleness in the dried or set state, resistance to or freedom fromtendency to crystallize or harden in containers during storage, etc., aswell as high permanent adposition or cement of advantageous combinedproperties. These and other objects and advantages will appear from thedescription taken as a whole.

For the sake oi' quickly illustrating specific embodiments '0! ourinvention, illustrative compositions or formulae will be given.

Formula 1 Pounds Solros rosin 900 "Foste" rosin 300 Dixi clay 1500Mineral'n 200 Denatured ethyl alcohol Petrobenzol Water 37 The "Solros"rosin employed, which is a well known article oi commerce, was a heattreated wood rosin having a melting point of 77 0., ball and ringmethod, and an acid number or the order of 125. The "Fosfo rosinemployed, also a well known article or commerce, was a wood rosin whichhad been treated with l of its weight of lime and had a melting point oi118 0., ball and ring method, and an acid number of the order of '75.The Dixie clay employed was a relatively low colloidal, but very fine,kaolin type clay or floury nature, found in large deposits in variousparts 0! the United States, for example North Carolina. The particlesize of the particular clay used was such that 98 percent thereof wouldpass a 300-mesh screen, which is a. small particle size compared withmany pigments, for example. The mineral oil employed had a Sayboltviscosity at 100 F. in the range of 500 to 530 seconds. The denaturedethyl alcohol is, of course, a well known article of commerce, thedenaturants being not necessarily but merely incidentally present. Thepetro-benzol is a petroleum hydrocarbon fraction boiling substantiallycompletely within the range of 140 .F. to 210 F.

The above composition has been employed to advantage for a number ofuses, e. g., for use in applying wall tile of various types such asasphalt tile and lacquered Masonite tile, or various ceramic, enamel,metal or other members, to the ceilings or walls of rooms. Some of theproperties of the above illustrated composition and advantages thereofover cements heretofore proposed for bonding wall tile and/or equivalentelements to ceilings or walls, are as follows:

(1) Ease of application-Because of its buttery character, the abovecomposition can be removed from the container and spread on the tile orwall surface without stringing and the cement stays in place withoutflowing.

(2) Long bonding range.Because the composition dries slowly and resistsformation of a skin on the surface thereof, application of the tile tothe wall can be made up to at least thirty minutes after the cement isspread. Most cements which have been suggested for this purpose skinover rapidly and the bonding range is usually not over to minutes.

(3) Higher initial ,wet strength-This is due to the material being moreor less of a plastic solid 'soithat thefcement resists tendency to flowuntil a certain critical load has been applied. Cements heretofore knownwhich have been suggested for such usage are quite liquid in characterand will normally flow under their own weight at room temperatures.

(4) Less tendency to cause "orange-peel of lacquered tile-The mostcommon type of cement heretofore known. suggested for use as a tilecement, is of such a nature as to soak through the back of such tile andcontact the polished lacquered surface. With these prior cements incertain cases this is due to a large quantity of certain types ofsolvents which have been necessarily employed to provide physicalcharacteristics needed during application. The composition hereinaboveillustrated contains a relatively small amount of alcohol and theformulation is such that the solvent is liberated slowly, thus greatlyminimizing or substantially completely obviating the difllculty, withrespect to causing orangepee on lacquered tiles and the like,encountered with prior cement compositions.

(5) Water-resistance.-The water-resistance of the composition of FormulaI is very good,

especially after several days of drying. This property is, of course,very important, as many installations are made in showers where waterand steam, in varying amounts, may get back of the tiles and in actualcontact with the adhesive. (It will be understood that thewater-resistance of the final dried film of the cement isbeing'discussed.)

(6) Adhesion characteristics.The composition of Formula I has goodwetting and adhesion to wood, metal, plaster, brick, concrete, etc.

(7) Colon-The above composition has an advantageous color, having acolor which might be described as straw color or of the general color ofpeanut butter or somewhat lighter, Various cements heretofore preparedhave, in general, been of a darker color, some of which we know beingdark gray in color. The advantages of a relatively light colored, cleanappearing cement, from the point of view of appearances in decoratedrooms in public buildings, especially where light colored or white tileor acoustical elements are employed, will be self-evident.

The minor amount of'water -employed in-the- I above formulacontributesin a very important way to preferred properties of theadhesive. This will be discussed more in detail hereinafter.

Another composition which we have developed which, in certain respects,is even superior to Formula I hereof, is as follows:

Formula II Pounds "Solros wood rosin 900 Fosfo" ros 300 Dixie clay 1800Mineral oil- 250 Alcohol Oleum spirits 138 Water 37 of formulaillustrated, apparently accounts to an important extent for thesomewhat'higher wet strength of Formula II over Formula I. The higherboiling hydrocarbon solvent employed in Formula II has the virtue ofkeeping down the rate of evaporation of solvent from the cement afterapplication, asfor example when the cement during drying may encounter atemperature of, illustratively, 140 F., more or less. Control of therate of evaporation is important so that the initial wet strength of thecement immediately after application will not drop off drasticallyduring drying due, for example, to the formation of bubbles behind 'thetiles or other objects bonded. The two differences just discussed, ofFormula II over Formula I, provide quite an appreciable distinction.

The composition of Formula II may, for example, be prepared as follows:The Solros" and "Fosfo rosins are charged into a suitable mixer, forexample a jacketed internal mixer, e. g., of the Werner-Pfieiderer orBaker-Perkins type. The mixer may be heated by introducing steam under apressure of 50 lbs/sq. in. gauge into the jacket of the mixer. It isnecessary to continue the mixing under temperature conditions of theorder illustrated for about 18 minutes, more or less, after which thesteam pressure in the jacket is dropped to about 20 lbs/sq. in. gauge.After mixing for about 10 minutes longer, approximately 80% of the totalamount of Dixie clay may be added and, after then mixing for about 40minutes, the steam is turned off and cold water is introduced into thejacket of the mixer. At this point the rosin has been fused orcompletely melted. The presence of clay during the melting of the rosinserves the function of increasing the volume of the mixture and alsoserves to stiffen the mixture to a point so as to increase themechanical working of the rosin which, correspondingly, increases therate of fusion or melting thereof. Next the mineral oil may be added,slowly at first so as not to break up the mixture or form lumps. As themix becomes softer, the rate of addition of the mineral oil may beincreased. In an ordinary procedure, it may require about 25 minutes toadd all of the oil. Next the hydrocarbon solvent (oleum spirits) may begradually added and the speed of the mixer increased to give fastermixing. The oleum may be gradually introduced over a period of about 5minutes. The alcohol is then added gradually, its introduction beingeffected overa period of about 5 minutes, more or less. The remaining 20percent of the Dixie clay may now be added and, by reserving this amountof the clay and adding it at this point, it serves the useful functionof helping to cool the batch be fore discharging the same from themixer. The mixture is quite limpid or fluid at this stage. The water isthen added and the mixing continued for about 15 minutes. The additionof the water to the foregoing mixture has the striking eifect ofthickening up the batch considerably and bringing it to the desiredconsistency, as opposed to rendering the batch more watery as one mightsuppose.

A making procedure in general essentially the same as that justdescribed in connection with Formula II may, if desired, be employed inconnection with the making of Formula I hereof. The petro-benzol may beadded at the same stage as was the oleum in the method just described.All of the clay of Formula I may be added at the point in the abovedescribed process where 80 percent of theclay of Formula II was addedor, if desired, a relatively small percentage of the clay of Formula Imay be held out and added after the addition of hydrocarbon solvent andalcohol.

Another method applicable in the formulation of the composition ofFormula H (also applicable in the making of Formula I) which has beenemployed will be presently described. In general it involves: (1)dissolving the resinous material (e. g., Solros and Fosfo rosins) in theoil, hydrocarbon solvent, and alcohol; and (2) mixing the clay and Waterinto this resin solution. In making the resin solution, the following isone illustrative procedure employed:

The Solros and Fosfo resins were melted over a gas fire in a suitablekettle, viz., a varnish makers kettle.

The mineral oil was added, with stirring, to the melted resin.

The hydrocarbon solvent (oleum) was next stirred in.

The alcohol was then added, after first cooling the mixture to the pointwhere the alcohol would not be lost due to boiling; viz. the mixture wascooled to approximately 160 F.

The resulting solution is thin enough so that it can be poured or pumpedquite easily at ordinary temperatures.

Another method of making this resin solution is to charge all theresins, oil, oleum and alco-- hol into a suitable churn or paddle typemixer and allow them to mix cold to a homogeneous solution. However,experiments have indicated that this method has the disadvantage that itis not easy to get all the resins into the solution in a reasonablelength of time by such procedure.

In the second step of this process the clay and water are mixed into theresin solution by employing a suitable heavy duty mixer. An advantageousmixer is one commonly known as a change-can mixer. It is also frequentlyreferred to as a pony mixer by such manufacturers thereof as the J. H.Day Company, Cincinnati, Ohio, as well as by various users thereof. Ingeneral it comprises a circular or cylindrical shaped can which rotatesand a multiple-prong fork-like stirrer that also rotates, and rotatesoff center in relation to the cylindrical can. Each prong periodicallycomes near to the inner circumference of the can during rotation oractuation of the mixer. The resin solution is weighed into the can andthe clay is added as fast as it can be taken up by the resin solution.After the clay has been thoroughly mixed in, the water is added andallowed to mix for about 5 minutes, more or less.

Certain tests indicate that Formula II when made according to theprocess just described, in a number of respects at least, hasapproximately the same characteristics as the composition of Formula IIwhen made by the first process described hereinabove. However thecomposition of Formula II, as made and sold in commerce heretofore, hasbeen primarily made according to the process first described herein.

It will be understood that the process last described is also applicablein making the composition of Formula I hereof.

While the above two compositions have been illustrated by specificmaterials and specific proportions of materials, it will be understoodthat substitute ingredients and variations in proportions of ingredientsare comprehended within the 'scope of the present invention. However itwill be understood that, in making such changes of ingredients or inchanging the proportion of the ingredients, due care should be taken soas to avoid rendering the resulting properties of the compositionunsatisfactory in this or that respect. For example, while the water maybe varied in amount. or replaced by a material or fluid of equivalentfunction, the functions served by the water are highly important. Itthickens up the cement and makes a plastic, buttery material out of thecement (which helps to give it wet strength), whereas without water orequivalent the cement is a relatively fluid material, merely a viscousliquid, which is not'suitable for such purposes as attaching acousticaltiles, or the like, to the ceilings of rooms, etc. The clay and water Fappear to have some united action, in the composition illustrated, whichaccounts for this result, at least in a measure. About 2 percent ofwater based on the clay, where the clay is of the type of the Dixie clay(i. e., low colloidal kaolin clay) employed, gives about the maximumeffect in producing buttery characteristics and increasing wet strength.If less water is used, in relation to the clay, a lower wet strength andgreater fluidity will normally result. On the other hand, wheresubstantially more than the amount of water indicated, based on theclay, is used, for example where more than about 4 percent of water,based on the clay, is used, the mass starts to become strin y. or ratherheavy and ropy and hard to handle. Glycerine and certain chemicallysimilar materials have the property of thickening up the batch somewhatthe same as water and may be used alone or in solution with water.However it will be obvious that the use of glycerine increases theexpense of the cement, which normally would be a needless sacrifice ofeconomy.

In respect to the buttery characteristics of the cement, in addition toclay, the resinous content of the cement is of importance. In general ithas been found desirable, when using Dixie" clay, to use from about 60to about parts of the resinous constituents, i. e., the bondingingredients, to 100 parts of clay. A wide variety of resinous materialsor bonding ingredients may be used. Where a combination of Fosfo andSolros" rosins are utilized as in Formulas I and II, and where the totalquantity of both types is kept at 1200 parts, the preferred ratios ofSolros to Fosfo, i. e., of high acid number to low acid number rosinmaterial varies from about 1:1 to about 4 1, and preferably from about2:1 to about 4:1.

High acid rosin type resins, e. g., having an acid number of 110-150,such as Solros heat treated rosin or rosin itself, may be used as thesole resinous constituent of our cements, to provide suitableapplication characteristics and various other characteristics for use,for example, in attaching tiles, acoustical elements, etc., to plaster,wood, concrete, etc.; but such cements,

' while quite satisfactory if applied soon after manufacture, show atendency to crystallize or harden in the container on long storage. Thetendency towards crystallization is somewhat less apparent with Solrosthan with other forms of rosins. Low acid rosin type resins orresinates, e. g., having an acid number of ,50-90, such as Fosfo rosinor other equivalent limed rosins or other metallic resinates may also beused as the sol resinous constituents of our cements. For example,Fosforosin may be substituted for the mixture of Solros and Fosfo rosinsin Formula II, in which case the alcohol is replaced by a somewhatincreased amount of oleum, for example, a total of 560 lbs. of oleum maybe used in the formula, and enough additional water is added to bringthe total water content to 60 lbs. in order to achieve properbutteriness of the somewhat more diluted formula.

The use of Fosfo rosin as the sole resinous constituent produces acement which dries more rapidly and to a somewhat harder final driedfilm than is the case with Formula II, for example. This is also true ofother equivalent metallic resinates, such as zinc resinates, which maybe used in place of the Fosfo rosin.

As will hereinafter be pointed out, other solvents, particularly themore active type of hydrocarbons such as the aromatic hydrocarbons, maybe desirably substituted for the petrobenzol or oleum. This isparticularly true where certain less soluble or less readily solublematerials are included in the composition, for ex ample as in FormulaVI. Still other solvents may also be employed for specific purposes;carbon tetrachloride has been used, for example, with Fosfo rosin, Dixieclay, mineral oil, and water, to produce a non-inflammable cementcomposition of buttery characteristics, but at a considerable increasein cost.-

The cements illustrated in the above two formulae .(that of Formula IIbeing even better than that of Formula I for most uses) have such a hightensile strength or cohesive strength that, in the wet state, they willsupport a weight of upwards of 70 lbs./sq. foot to the surface of aceiling. Also, they will continue to support such a weight duringdrying. This is a notable strength for a composition of the generalnature shown hereinabove, not containing rubber or equivalent rubberypolymer.

Another example of a plastic adhesive cement composition of butteryconsistency, similar to that of Formula II except for the use ofordinary rosin in place of heat-treated rosin, as hereinbeforeindicated, may consist substantially of the following ingredients inapproximately the proportion indicated:

Another composition which difiers from those above illustrated, forexample in the respect that Water some rubber is employed, is shown bythe following formula: 7

*Formula III Pounds Solros rosin 585 Fosfo rosin 195 Reclaimed rubber 1195 Dixie clay 1,300 Mineral oil 195 Petro-benzol 400 Water 26 Theparticular reclaim employed in the above formula is a redinner tubereclaim made by the alkali digester process. Various inner tube reclaimsand/or other reclaims, or raw rubber such as latex crepe or smokedsheet, may be employed, usually, however, with some change in theformulation of the adhesive.

The compositio of Formula III may be made generally according to thefirst procedure described hereinabove for compounding the composition ofFormula II. However the reclaim (after first working it on a rubber millto render it more plastic and easier to disperse) is introduced into theheavy duty internal mixer (e. g., Baker-Perkins type) before or at thesame time as the Solros and Fosfo rosins are introduced. By way offurther slight distinction to the procedure hereinabove described, it isdesirable to mix the batch of rubber and resins longer before adding theoil and solvents, in order to get the rubber thoroughly dispersed and torender the batch uniform, which will be evident to the operator.

Although the composition of Formula III may be employed as a tile cementor for like purposes, the composition of Formula II (or ofFormula I isusually more preferable as a tile cement. However such cements asillustrated in Formula 111 have a definite advantage where a tile cementis desired with increased shock-resistance in the form of the dried filmand one which has less change in body or stiffness with changes intemperature. Additionally, the above composition may be employed toadvantage for certain other uses such as, for example, to adhereso-called structural glass (e. g., Carrara") to another surface such asthat of wall board.

Another rubber-containing cement, which we have prepared, which also hasutility, for example. as an acoustical cement, is the following in whichall parts are by weight: Formula IV Parts Solros wood rosin 1,050 Fosforosin 150 Heated tube scrap 300 Mineral oil-Sayb0lt viscosity at F. of

500 to 530 seconds 300 Dixi clay 2,000 Ethyl alcohol 60 Oleum spirits405to 425 F. boiling range 420 38 The above composition, in addition toincreased shock resistance, has several other advantages over suchcompositions as those of Formulae I and II. including betterheat-resistance, better handling properties at low temperatures (e. g.,35 F.) and faster increase of strength of the cement bond afterapplication.

In a modified formulation of the above composition we employed somewhatless Dixie clay (about 1900 parts) and also somewhat less ethyl alcohol(about 30 parts). course. substantially wider variations than this inthese and other ingredients are contemplated, as will be generallyunderstood from'the discussion hereinabove, and from this application asa whole.

The heated tube scrap was prepared by heating scrap red inner tubes inan autoclave in contact with steam at 160 lbs. per square inch gaugepressure for a period of 16 hours. At the end of this time the tubeswere very materially softened so that they could be dispersed in theresin-clay mixture. The resulting heated tube scrap was then worked onan ordinary rubber mill and a part of the Dixie clay of Formula IV andalso a part of the Fosfo rosin was incorporated with the rubber duringmilling. Half as much Dixie clay as tube scrap was first added andmilled with the heated tube scrap for about 20 minutes, in order tostiffen mixer. The milled batch may contain ingredients, for example, inthe following proportion:

Parts Heated tube scrap 100 Dixie clay 50 Fosfo rosin 15 The remainderof the procedure for formulating the composition of Formula II may, forexample, be similar, in general respects, to that first describedhereinabove in connection with Formula II. It will be understood that,in adding ingredients to the batch in the internal mixer, the amounts ofclay and Fosfo rosin added with the tube scrap in the milled batch aresubtracted from the amount shown in Formula IV, so that the totalamounts in the resulting cement composition will be as illustrated inFormula IV. Here again, as described in connection with Formula III, itis necessary to'mix the rubber composition longer before the addition ofthe oil and solvent in order to get a smooth dispersion of the rubberand to avoid the formation of rubber lumps.

It is to be noted that theresults produced by use of the heated tubescrap, as just illustrated above, cannot be attained or duplicated bythe use of ordinary commercial types of reclaim rubber. That is, thefinished cement made with the heated tube scrap has advantages over anotherwise comparable cement in which a conventional reclaim is employedinstead of the heated tube scrap of the present invention.

It will be understood that the second method hereinabove described indetail for compounding the components of Formulae I and II, which amongother things contemplated employing a change-can or pony mixer, wasespecially ining quite tough, with pronounced rubbery properties andalso with increasing strength of bond when dried. As little as 50 ,partsof solid rubber, as latex, to 1200 parts of resin is enough to have avery significant effect on the properties of the resulting composition.Apparently the latex dispersion breaks when the same is added to theresinous composition in the internal mixer, giving an interlacingnetwork of rubber which toughens the cement. However such a compositionis less desired by most users, for example as a tile cement or foranalogous purposes than Formulae I and II for the reason that the samehas a tendency to be somewhat stringy.

The following formula illustrates a variation of Formula I hereinabovedescribed.

Formula V Pounds Solros rosin 3'75 Fosfo rosin- Korite" asphalt 700Dixie clay 1,500 Alc hol 90 Petrobenzol- 350 Water 37 It will be notedthat the amount of resins have been reduced as compared with Formula Iand a substantial amount of asphalt has been used. The particularasphalt illustrated is a dark colored blown residual petroleum asphalthaving a melting point or softening point of approximately 200 F., balland ring method.

The composition of Formula V is more economical than that of Formula Iand it resembles Formula I quite closely in certain properties but,significantly, not in color. The relatively lighter color of Formula I,i. e. its straw color or light peanut butter color, is consideredimperative by many users of tile cements, whereas the composition ofFormula V is relatively dark in color. The composition of Formula V,however, dries somewhat faster than that of either of Formulae I or IIand has very good ageing properties. It remains more plastic thanFormula I when heated at temperatures around F. to F.

The color of the composition of Formula V may be made somewhat lighterby, for example, in lieu of the asphalt specified, employing materialsthat are some times referred to as petroleum resins and some times asAlbino asphalts. These materials are at the present time quite expensiveas com-pared with the ordinary asphalts, or even with wood rosin.However, for certain usages, the asphalts and petroleum resins have anadvantage over regular wood rosins in that they do not contain anysignificant amount of free acids, which makes them resistant to alkalimaterials. As plasters and concretes often contain some alkali that hasa tendency to attack wood rosin adhesives under certain conditions, theuse of a relatively inert resin' such as the Albino asphalts havecertain advantages.

However, except where the conditions are relatively acute, no practicaldifficulty whatever has been experienced in employing such compositionsas those Qf. Formulae I, H, etc., hereinabove illus- 11 trated, toattach acoustical tiles or other tiles or members to plaster, concrete,or other surfaces. It will be apparent that abietate type resins such asthe combinations of Soil-cs" and "Fosfo" resins specified in FormulasI-IV and, in con- .juncticn with asphalt, in Formula V, provide distinctadvantages where low cost is an important consideration. It is to benoted that many other resins or combinations thereof may be used toprovide cement compositions of considerable utility for the same orspecial purposes, as indicated by the following additional specificformulas.

Formula VI Pounds Rubbery chloroprene polymer 300 Morpholine 15Oil-soluble heat-advancing phenolaldehyde The rubbery chloroprenepolymer, e, g., Neoprene, is softened by milling and by incorporation ofthe morpholine and is then mixed cold in the heavy duty internal mixerwith the resins and pigments. The solvent is finally added and worked inwell, producing a fluid mixture. Addition of the water then brings aboutthe desired conversion of this fluid composition to a buttery, plasticsolid state well adapted for use as a tile cement. After application,and in the dried form, this cement has superior bonding power and ishighly resistant to shock while still being hard and nondeformable.

As one example of a suitable oil-soluble heatadvancing phenol-aldehyderesin for use in the above formula may be listed an alkali catalyzedpure phenolic resin produced from mixed alkylsubstituted phenols andformaldehyde. In this formula, the use of a solvent high in aromaticcontent is found desirable due to the presence of the chloroprenepolymer; a suitable solvent may have a distillation range ofapproximately 200- 265" F. and an approximate aromatic blending value of50 percent.

In another formula, a small amount of Fosfo rosin is used together witha larger amount of a chlorinated paraiiin, as follows:

Formula VII Parts Highly chlorinated .paraiiin 120 Carcass stock reclaimrubber 50 Fosfo rosin 50 Dixie clay 200 Water 4.5 Petro-benzol 80 i2important fields of utility due to this additional property.

Formula VIII Parts Phenol-aldehyde resin as in Formula VI 200 Dixie clay300 Heavy mineral oil 41 Oleum spirits Water 10 A heavy mineral oil,such as illustrated in Formula IV above, is a suitable oil for use inFormula VIII, just given. Additionally, cements such as Formula VIII areresistant to high tem- Peratures, since the phenolic resin used in thisformula sets up to an increased melting point on subjection to heating.

Still other cements have been made in which as the sole resinousconstituent there was employed ester gum (commercial lycerol abietate),a high melting pure hydrocarbon thermoplastic terpene resin of low acidnumber, dehydroabietic acid having a melting point of about 65 C. and ahigh resistance to oxidation, and even soft resins such as methylabietate and hydrogenated methyl abietate. Natural gums, such as Manilagum, have also been used, for example to replace part of the resins ofFormula I or II; but Manila gum is relatively high in cost and tends toreduce the plasticity or yieldability of the final dried film.

I all cases, the cement prior to the addition of water was soft orliquid, and if applied to a ceiling or wall surface would flow readilyunder its own weight or the weight of an attached tile or the like.After incorporation of' water, as shown in the various formulas, thecement wa firm and buttery; it could be readily spread in place, butremained as a plastic solid which, under the weight of even quite heavytile sections, did not flow or change position, and therefore, bothduring drying and later, held the tile firmly in position.

The amount of Dixie clay or equivalent which is employed in thesevarious formulas is fairly critical in producing a good tile cement. Thevarious formulae hereinabove presented illustrate different amounts ofclay. They do not illustrate the limits of variation, but do illustratePreferred proportions. If too much clay is employed, the wetting in ortransferability" of the cement to tile, plaster, etc., is impaired. 0nthe other hand, if too little clay is employed, it is not possible torender the cement sufllciently buttery or still when water is added,with the result that the wet strength of the cement and its applicationcharacteristics are impaired.

Other clays or other materialsmay be used in place of some or all of theDixie clay, if desired. However, a finely divided, low colloidal kaolinclay has, in general, proved most satisfactory thus far. Certain claystend to form a jelly-like structure, which is not desired, while Dixieclay provides a cement having more slip," which is highly desirable incements to be used as tile cements and the like. China clay, Par clay,"and Georgia clay are all examples of other suitable low colloidal kaolinclays.

Clays mentioned hereinabove are illustrative of clayey inorganicmaterials broadly, which generally have S102 and A: in combination,whether naturally occurring products or manufactured products, which maybe employed, in the combination herein illustrated and defined, inmaking our tile cements.

If a minor proportion of a. somewhat higher colloidal clay is used alongwith a. low colloidal clay such as Dixie clay, then a somewhat higherratio of water to clay than shown, for example, in Formula II may beused to give best results. On the other hand, if a low colloidal claysomewhat coarser than Dixie clay is used, ordinarily a somewhat lowerratio of water to clay than i1- lustrated in Formulae I and II will giveoptimum results.

It will be noted that Dixie clay and the like, although water-insoluble,are nevertheless hydro- Dhylic agents of finely divided or trituratednature. The preferred equivalents of Dixie clay are substantiallywater-insoluble but hydrophilic materials which are non-fibrous orsubstantially so, materials capable of absorbing water and forming auniform or pasty mixture therewith being especially contemplated.However, the present invention does not preclude the addition of fibrousmaterials but the same are not the equivalents of Dixie clay and thelike. The stiflening of the cement upon the addition of water ashereinabove described indicates some pronounced physical orphysico-chemical interaction between the clay and other ingredients ofthe cement.

Other pigments or fillers may be used in addition to the various claysfor certain specific purposes, as desired. Thus the asbestine added inFormula VI increases the hardness of the dried cement coating.

In order to avoid cracking and fracturing of the dried resinous cementof our invention, the normally brittle resinous constituents arerendered non-brittle by the addition of a suitable toughening agent orplasticizer for the dried composition. Mineral oil serves this functionin Formulas I, II and VIII, and also, in conjunction with rubber, inFormulas III and IV.

Many other plasticizers including drying, semidrying, and non-dryingvegetable oils or the like have also been tried, comprising castor oil,palm oil, cocoanut oil, linseed oil and soybean oil, and may be employedin lieu of the hydrocarbon or mineral oil illustrated, These materialsare considered as good as, and possibly somewhat better than mineraloils in respect to plasticizing, i. e., rendering less brittle, therosins or like resins; however their comparatively high cost makes theiruse undesirable. Pine tar, pine tar oil, japan wax, paraflin wax, etc.,have also been tried in place of mineral oil but, although they do actto decrease the brittleness of rosins or like resins, they aretechnologically inferior to mineral oil. In addition, mineral orhydrocarbon oils have the virtue, particularly as compared to the dryingoils, of remaining in more or less unchanged state over a long period oftime in the final dried film or coat of cement.

In Formula V, asphalt in relatively large amount acts as a plasticizeror brittleness-reducer for the brittle rosin or resinous constituentsand also is a preponderant proportion of the resinous phase of thecement. The processed rubber of Formulas III and IV, the synthetic rubber (polychloroprene) of Formula VI, and the combination of reclaimrubber and chlorinated paraflin of Formula VII, all provide or add tothe toughness, i. e., the reduction in brittleness, of the dried cementcomposition which is necessary for its best success in maintainingacoustic tiles and the like in position on walls and ceilings.

The alcohol employed in certain of the listed formulas serves theadvantageous function of aiding in keeping the resins in solution andlending stability to the cements, as well as serving to improve thewetting in characteristics of the latter. It alsoimproves the waterresistance of a wet film of the cement very noticeably, the cement evenbecoming somewhat firmer under water, due possibly to removal of thealcohol by diffusion in the water. In lieu of ethyl alcohol, methylalcohol, propyl alcohol and various other volatile alcohols may beemployed. Additionally other materialssuch as ethylene glycol monoethylether, ethylene glycol monobutyl ether, diethylene glycol monoethylether, etc have been found to act like alcohol to a considerable extentbut tend to make the cement set up more slowly, which is ordinarily adisadvantage. Additionally it is likely that methyl acetate, ethylacetate, etc., would serve, at least to some extent, to provide one ormore of the functions of ethyl alcohol. However, in general, wherealcohol or similar solvent modifier is found to be desirable for onereason or another, we prefer to use ethyl alcohol because of its readyavailability and also because of its advantageous properties. Incompositions such as those of Formula I, it appears that there may besome short 'of a quasi-chemical or physico-chemical interaction betweenthe ethyl alcohol or equivalent and the Fosfo rosin or equivalent. Also,the consistency or stiffness of the cement for a given solids content isinfluenced to some extent by the ethyl alcohol.

Alcohol or the like is not, however, to be considered an essentialingredient of our novel cements, particularly where various resins otherthan the rosin type resins are used. Thus in Formulas III, VII and VIIIa gasoline-type solvent by itself is found to be effective; Formula VI,with a diificultly soluble ingredient, requires a hydrocarbon solvent ofsomewhat improved solvency characteristics.

It will be apparent that various organic solvents may be employed inplace of some or all of the particular solvents illustrated in the aboveformulae. Where substitute solvents are employed, they should be chosenwith reference to their volatility, drying properties and othercharacteristics so as, for example, not to adversely affect the dryingcharacteristics of the resulting cement. By way of illustration, where asolvent which is too volatile is employed and the same is used to attachtiles, for example, to an underlying surface, such as a, ceiling, thesolvent in evaporating relatively rapidly tends to form bubbles and toforce the bonded surfaces apart during the course of the drying period.In order to have a large factor of safety, it is important that thecement have a high cohesive or tensile strength during thesettingcperation and in accomplishing this it is in turn important thatthe bond between tiles and the like and a ceiling or wall be not brokenat various points due to too rapid evaporation of solvents. For example,benzol or like coal tar solvents are satisfactory substitutes for oleumspirits etc. in terms of solvent action, but their higher cost andrelative toxicity make the same much less desirable than petroleumfractions of suitable volatility in those cases where the latter typeare of suiliciently active solvency for the particular composition inquestion.

While the present invention has been illustrated in various details, itwill be understood that it is not to be limited thereby and that wecontemplate all embodiments within the scone m the 15 presentapplication, taken in the light of the prior art. I

What we claim is:

1. A plastic adhesive composition adapted to secure acoustical tiles towalls and ceilings, a d of yieldable, plastic, non-brittle character inthe form of the dried film comprising: a yieldable, plastic, non-brittleresinous bonding base material comprising a brittle soluble resinousmaterial and a compatible organic toughening agent therefor; a volatilehydrocarbon solvent; a finelydivided clay, in an amount by weight atleast approximately as great as said resinous base material but: notsubstantially exceeding one-half that of the entire said adhesivecomposition; and water, in an amount by weight of the order of 2 to 4percent of that of said clay; said resinous base material making uproughly one-third of the entire said adhesive composition; and saidvolatile solvent being present in substantial but lesser amount thansaid resinous base material; said adhesive composition being of buttery,plastic consistency and of wet strength suitable to hold tiles to wallsand ceilings during setting.

2. A plastic adhesive composition adapted to secure acoustical tiles towalls and ceilings, and of yieldable, plastic, non-brittle character inthe form of the dried film, comprising: a yieldable, plastic,non-brittle resinous bonding base material comprising a brittle solubleresinous material and a compatible oil plasticizer therefor; a

I volatile hydrocarbon solvent; a finely divided hydrophilic clayeyinorganic material having S102 and A120: in combination, in an amount byweight at least approximately as great as said resinous base materialbut not substantially exceeding one-half that of the entire saidadhesive composition; and water, in an amount by weight of the order of2 to 4 percent of that of said clayey material; said resinous basematerial making up roughly one-third of the entire said adhesivecomposition; and said volatile solvent being present in substantial butlesser amount than said resinous base material; said adhesivecomposition being of buttery, plastic consistency and of wet strengthsuitable to hold tiles to walls and ceilings during setting.

3. A plastic adhesive composition adapted to secure acoustical tiles towalls and ceilings, and

of yieldable, plastic, non-brittle character in the form of the driedfilm, comprising: a tough, yieldable, non-brittle resinous base bondingmaterial, dissolved in a volatile hydrocarbon solvent therefor; a finelydivided hydrophilic clayey inorganic material having S102 and A120: incombination, in an amount by weight at least approximately as great assaid resinous base material but not substantially exceeding onehalf thatof the entire said adhesive composition; and water, in an amount byweight of the order of 2 to 4 percent of that of said clayey material,to convert the otherwise soft and flowable composition to a buttery andplastic consistency;

said resinous base material making up roughly one-third of the entiresaid adhesive composition; and said volatile solvent being present insubstantial but lesser amount than said resinous base material; saidadhesive composition being of buttery, plastic consistency and of wetstrength suitable to hold tiles to walls and cellings during setting.

4. A plastic adhesive composition adapted to secure acoustical tiles towalls and ceilings, and oi. yieldable, plastic, non-brittle character inthe form of the dried film, comprising: a yieldable, plastic,non-brittle resinous bonding base material comprising a resin containingthe abietate radical and an oil plasticizer for said resin; a volatilehydrocarbon solvent; a finely divided clay, in an amount by weight atleast approximately as great as said resinous base material but notsubstantially exceeding one-half that of the entire said adhesivecomposition; and water, in an amount by weight of the order of 2 to 4percent of that of said clay; said resinous base material making uproughly one-third of the entire said adhesive composition; and saidvolatile solvent being present in substantial but lesser amount thansaid resinous base material; said adhesive composition being of buttery,plastic consistency and of wet strength suitable to hold tiles to wallsand ceilings during setting.

5. The new and improved construction comprising tiles joined to a solidwall surface by the non-tacky but firmly adherent dried residue of aplastic adhesive composition as defined in claim 4.

6. The new and improved construction comprising tiles joined to a solidwall surface by the non-tacky but firmly adherent dried residue of aplastic adhesive composition as defined in claim 3.

GORDON F. LINDNER. HARVEY J. LIVERMORE.

REFERENCES CITED 45 The following references are of record in the fileof this patent:

UNITED STATES PATENTS Bennett's Chemical Formulary, 4th vol., page 25(top of column 2), 1939.

